put more variables into Makefile-common.in
More Makefile unification and disambiguation

* use the same Perl that invoked Configure*.pl always
* avoid NQP_SOURCES
[build] avoid more name collisions
[build] unify NQP_MO_COMBINED
[build] unify P5QREGEX_COMBINED
[build] more Makefile unification
[parrot] fix p5regex support build
[build] unify QREGEX_COMBINED
[build] some more moar/JVM unification
[build] avoid Makefile variable clashes

... between JVM and MoarVM